The present disclosure relates to joined pipe flanges and, more particularly, a fluid control device secured between pipe flanges. Even more particularly, the present disclosure relates to a fluid control assembly adapted to be secured between two pipe flanges and including flange spacers.
Pipes and fluid control devices, such as valves and pumps, are common in the utility, refinery, manufacturing, chemical and petrochemical industries for transporting fluids. Pipes often include attachment flanges at their ends, and fluid control devices are secured between the pipe flanges, usually using bolts. In such cases it is desirable that stresses be applied to the pipe flanges evenly, that the fluid control device is properly aligned with the pipes, and that the bolts are correctly torqued or loaded.
For example, fiberglass reinforced pipe ("FRP") as well as other plastic piping systems and components provide many industries with a corrosion-resistant, less costly replacement for metal piping. However, since plastic piping is, by its nature, not as strong as metal piping, flanges of plastic piping may be more susceptible to cracking upon uneven loading or rotation of the flanges.
Improper alignment of the fluid control device with the pipes could interfere with operation of the fluid control device. Butterfly valves, for example, typically include a generally cylindrical body which is connected into a pipe line by being clamped between two pipe flanges. The valve body has a flowway therethrough and a valve element is mounted in the flowway for movement from a closed valve position to an open valve position. In the open valve position, the valve element can extend out of, and beyond the valve body. Thus, correctly aligning the valve with the pipes is necessary to prevent interference between the valve element and the pipe flanges during movement of the valve element between the closed and open positions.
In addition, bolt creep and improper loading or torquing of bolts joining the pipe flanges to the fluid control device can result in a loosening or weakening of the joint. Bolt creep is a condition wherein bolts naturally loosen over time due to machine vibration and thermal expansions and contractions, for example. Improper loading can occur due to inaccurate torquing of bolts holding flanges together.
Thus, what is desired is a fluid control assembly for clamping between pipe flanges that provides reduced flange stresses and easy alignment with the pipes. What is also desired is a fluid control assembly wherein bolt creep is reduced or eliminated, and wherein bolt loading is made easy and convenient, both in the assembly of the joint and in the maintenance of the joint.